Patients with chronic obstructive pulmonary disease (COPD) may suffer dyspnea when performing unsupported arm exercises (UAE). However, some factors related to the tolerance of the upper limbs during these exercises are not well understood. Our investigation was to determine if an unsupported arm exercise test in patients with COPD accomplishing diagonal movements increases lactic acid levels; also, we assessed the metabolic, ventilatory and cardiovascular responses obtained from the unsupported arm exercise test. The study used results of maximal symptom limited tests with unsupported arms and legs performed on 16 patients with COPD. In order to do the test, some metabolic, respiratory and cardiovascular parameters such as oxygen uptake (VO(2)), carbon dioxide production (VCO(2)), respiratory rate (RR), pulmonary ventilation (VE), heart rate (HR) and blood pressure (BP) were measured during the exercise tests. Furthermore, blood lactate concentration was measured during the arm test. We detected a significant increase in the mean blood lactate concentration, VO(2), VCO(2), VE and RR from the resting to the peak phase of the UAE test. The mean values of VO(2), VCO(2) and VE obtained at the peak of the UAE test corresponded to 52.5%, 50.0% and 61.2%, respectively, of the maximal values obtained at the peak of the leg exercise test. In comparison, the mean heart rate and systolic arterial blood pressure were significantly lower at the peak of the UAE test than at the peak leg exercise test and corresponded to 76.2% and 83.0%, respectively. Unsupported incremental arm exercises in patients with COPD increases blood lactic acid levels.